Various 1,4-benzodiazepine compounds including nitrazepam, diazepam, medazepam, estazolam, and triazolam have been used practically as hypnotics, minor tranquilizers, or psychotropic agents. Recently, mental disorders have shown a tendency to rapidly increase as the human society is complicated. The present inventors have investigated to develop drugs acting on the central nervous system (hereinafter abbreviated as "CNS") more effectively and which are broadly applicable to mental disorders, and have succeeded in developing novel CNS drugs see our copending (U.S. patent application Serial No. 91,814 filed Nov. 6, 1979 now U.S. Pat. No. 4,297,280). The present invention provides a novel type of CNS drugs i.e. 4,1-benzoxazepines having potent central nervous system actions. The compounds having 1,4-benzodiazepine structure are known to show a variety of CNS actions, but 4,1-benzoxazepine derivatives are not so generally active as CNS drugs. Some 4,1-benzoxazepine derivatives have been described in German Pat. No. 1,545,639, U.S. Pat. No. 3,346,638, Farmaco. Ed. Sci., 18, 815 (1963) and Ann. Chem., 1978, 1241. The compounds of this invention shown hereinafter are novel and quite different from the above-cited known 4,1-benzoxazepine derivatives in potency and diversity of the CNS actions and in chemical structure.